Flutter 构建 Android 错误：评估项目“:app”时出现问题。没有方法签名

Question

我目前正在尝试将我的 Flutter 应用程序上传到 Play 商店。我按照 Flutter 文档上的说明进行操作。但是当我运行命令“flutter build appbundle”时，出现以下错误：

评估项目“:app”时出现问题。无方法签名：build_bobankfptw27tkl4q05osmwsd.android() 适用于参数类型：(build_bobankfptw27tkl4q05osmwsd$_run_closure2) 值：[build_bobankfptw27tkl4q05osmwsd$_run_closure2@103337d8]

这是我的 build.gradle 文件的内容。

def localPropertiesFile = rootProject.file('local.properties')
if (localPropertiesFile.exists()) {
    localPropertiesFile.withReader('UTF-8') { reader ->
        localProperties.load(reader)
    }
}

def flutterRoot = localProperties.getProperty('flutter.sdk')
if (flutterRoot == null) {
    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
}

def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
if (flutterVersionCode == null) {
    flutterVersionCode = '1'
}

def flutterVersionName = localProperties.getProperty('flutter.versionName')
if (flutterVersionName == null) {
    flutterVersionName = '1.0'
}

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"

def keystoreProperties = new Properties()
def keystorePropertiesFile = rootProject.file('key.properties')
if (keystorePropertiesFile.exists()) {
    keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
}

android {
    sourceSets {
        main.java.srcDirs += 'src/main/kotlin'
    }

    defaultConfig {
        applicationId "fr.mediprest"
        minSdkVersion 18
        targetSdkVersion 30
        compileSdkVersion 30
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
    }

    signingConfigs {
        applicationId "fr.mediprest"
        minSdkVersion 18
        targetSdkVersion 30
        compileSdkVersion 30
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
        release {
            keyAlias keystoreProperties['keyAlias']
            keyPassword keystoreProperties['keyPassword']
            storeFile keystoreProperties['storeFile'] ? file(keystoreProperties['storeFile']) : null
            storePassword keystoreProperties['storePassword']
        }
    }

    buildTypes {
        release {
            signingConfig signingConfigs.release
        }
    }
}

flutter {
    source '../..'
}

dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
}

有人知道可能导致此错误的原因吗？